There has been recent progress in the guiding and focusing of light beyond the diffraction limit through the use of surface plasmons. Because of the potentials afforded by greatly increasing the optical energy density, plasmonic technology advances have created a new field known as plasmonics. There is a good deal of significant prior art with most of the work relating to applications such as near-field optical microscopy, surface enhanced Raman spectroscopy, heat-assisted magnetic recording, and optical data storage. The prior art specifically relating to patterning of metal films on the facets of laser diodes also exists. A. Partovi, et. al., teaches a “High-power laser light source for near-field optics and its application to high-density optical data storage,” in, Appl. Phys Lett., vol. 75, no. 11, pp. 1515-1517, 1999. F. Chen, et. al., teaches “Imaging of optical field confinement in ridge waveguides fabricated on very-small-aperture laser,” in Appl. Phys Lett., vol. 83, no. 16, pp. 3245-3247, 2003. E. Cubukcu, et. al., teach a “Plasmonic laser antenna,” in Appl. Phys Lett., vol. 89, pp. 093120-1-3, 2006. These efforts were directed to increasing the near-field intensity by focusing plasmonic waves at a single location on the facet of single-lateral-mode laser diodes.
Nanorods have been grown on a surface to control an index of refraction. J. Q. Xi et. al., teaches “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection.”, in Nature Photonics, vol. 1, pp. 176-179, 2007. This technology is used to create a spatially graded index which would allow for wide-band antireflection coatings. In addition to nanorods, plasmonic Bragg gratings have been disclosed. A. Boltasseva et al., teaches “Compact Bragg Gratings for Long-Range Surface Plasmon Polaritons,” in the Journal of Lightwave Technology, v. 24, no. 2, pp. 912-918, 2006. A Bragg grating was used to reflect plasmonic waves of various frequencies. Thus, the plasmon is the input that hits the plasmonic grating, and plasmons of certain frequencies are reflected while other plasmons are transmitted. This Bragg grating functioned entirely in the plasmonic regime. Plasmonic gratings have also been made with very high efficiency of plasmon generation, while uncoupled light is specularly reflected as in the conventional optical facet. Prior art Bragg gratings are disadvantageously limited to the plasmonic regime without the ability to expand, shape, or manipulate the modes of the plasmons.
The conventional high power laser diode does not fill its laser gain cavity during standard operation. Instead, the optical mode forms a filament due to the optical and gain dynamics of the device. The position of this lasing filament is not static but rather moves through the device, creating multimodal hot-spots and thermal lenses which accelerate failure of the device. These and other disadvantages are solved or reduced using the invention.